Fire chiefs have requested military assistance to fight the worst English wildfire in living memory that has left residents in Manchester struggling to breathe as smoke sweeps down from Saddleworth Moor into the city.

Fire chiefs have requested military assistance to fight the worst English wildfire in living memory that has left residents in Manchester struggling to breathe as smoke sweeps down from Saddleworth Moor into the city.

Dozens of homes were evacuated and schools closed yesterday as the blaze continued to spread for a third day over 800 hectares of dry moorland.

The army was drafted in yesterday as 100 firefighters from two forces tackled the blaze, which may have started when sparks from off-road motorcycles set light to the grass.

The blaze was so severe it created an ash cloud over Manchester, lowering temperatures in the city by 3C, while the smoke plume over the area was clearly visible on Nasa satellite images.

Experts warned it could be weeks before the blaze is brought under control, because the peat below the surface could be smouldering and catch fire again even when it seems the fire is out.

Dave Keelan, director of emergency response at Greater Manchester Fire and Rescue Service, said: "We have been liaising with a military adviser on the scene and following those discussions we have requested military assistance from the Ministry of Defence.

"There's still a lot of smoke from the fire, but air quality levels are being monitored regularly in different locations. Air quality is currently at a safe level and therefore residents have been let back into their homes."